Originally Posted by BoringGuy
If he decided that she is so wonderful that he wants to be with her forever and is willing to make the sacrifice of discontinuing the practice of non-monogamy, then you can't really control that or put a stop to it, no matter what you do.
Absolutely, nor should you!
I want my partners to be happy, if that happens to mean that they don't want to see me anymore then so be it. Granted, I'll be sad for a period of time but I should still take the time to rejoice that someone I love is moving on to something that brings them joy.